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NSSI Lakes Data: Mapping Winter Liquid Water Availability in Lakes on the North Slope Coastal Plain of Alaska Using Synthetic Aperture Radar (SAR)

Shapefiles and Report

The North Slope coastal plain represents a unique landscape that is characterized by permafrost and an immense number of freshwater lakes of varying sizes and depths. These lakes provide habitat for fish and wildlife species, support subsistence resources for use by local populations, and serve as freshwater supply for industrial development. The ability of resource managers to effectively balance these uses depends on our understanding of the capacity of these lakes to serve as water storage and as well as our understanding of their function as habitat.

Each lake within the North Slope coastal plain study area was classified for the presence of liquid water below ice using synthetic aperture radar (SAR) data for late winter (April 2009). C-band radar from the European Remote Sensing satellite (ERS-2) was used in this analysis. Spatial resolution of the SAR imagery is 25m. Orthorectification accuracy of SAR images varied consequently a 50m buffer was evaluated as part of accuracy evaluation to account for horizontal registration error. Final overall classification accuracy was determined using 18,753 bathymetric locations from 105 lakes. Overall classification accuracy of these bathymetric locations as frozen/unfrozen (inferred from depth) was 89%.

Two shapefiles and final documentation are included in this data release. One shapefile (NSLakes.shp) provides perimeters from NHD of all lakes that were considered in this analysis and the other shapefile (NSLake_unf.shp) provides the areas within those lakes that were classified as containing liquid water below ice. The report document provides a description of data products, data processing, accuracy evaluation and potential applications and is available for download separately below.

These products are experimental and should be used with caution. The products may be useful for reconnaissance level planning or logistics planning to identify lakes expected to remain unfrozen through winter. The user is encouraged to report results of field validation or application of these products to jgrunbla@alaska.edu.